1. Field of the invention
This invention relates generally to base station control systems; and, more particularly, to feedback reporting systems for returning the operational status of said base station equipment to a remote control terminal.
2. Description of the prior art
Oftentimes a radio transmitting and/or receiving base station will be remotely located from the control terminal for said base station. The operation of the base station equipment is then controlled remotely from the control terminal. It is advantageous that the base station equipment have signals which are coupled to the control terminal only by means of audio signal lines, which means that no direct current connections are provided between the control terminal and the base station. All information signals and control signals are then coupled from the control terminal to the base station by audio frequency lines. A system using a single audio channel for providing voice signals and for providing control signals to a base station from a control terminal is disclosed in U.S. Pat. No. 3,577,080 issued to Gary A. Cananalte and assigned to the assignee of the present invention. However, the system disclosed in that patent was a one-way system in the sense that no reply signal was returned (or feedback) from the base station to the control terminal, indicating the correct receipt of the control signal and proper signal operation. For example, no indication was reported to the remote control site that the base station transmitter was actually keyed, that a predetermined output power level was established, or that the transmitter was operationally capable of being modulated. In order to assure a high overall system reliability percentage, it is necessary that some sort of reply signal system be used. Reply signal systems of the prior art used direct current signalling schemes as well as separate feedback signal lines. Obviously, these prior art systems are expensive and not easily incorporated into existing systems having only audio frequency coupling between the base stations and the control terminals.